This will just copy the screen of the one you've got on the cable so mirroring.
Yes, would copy the image I think, if you used it for the projector and TV you would probably be ok. it is unlikely you are going to watch seperate stuff on them both at the same time.
This is what I was thinking. I would never be running both the TV and PJ at the same time or attempting to display different things. However, I have ready many stories that people used these splitter cables and the video cards were unable to detect any devices and hence unable to display any images on them.